Cal. CORP § 14315

(a) The mutual water company described in Section 14311 shall provide at least a minimum level of water service to its customers for fire protection purposes as an inherent part of the water system design in accordance with the standards set forth in this section. The standards set forth in this section are the minimum levels of water service that the mutual water company shall provide and shall not preclude the mutual water company from designing a fire protection system that meets higher standards, nor preclude any governmental agency from setting higher standards in any area subject to its jurisdiction. A mutual water company may request a fire protection agency to approve a fire protection system that does not meet the standards set forth in this chapter upon a showing by the mutual water company that the proposed system is adequate for fire protection purposes.

(b) In the initial construction, extension, or modification of a water system, any one of which is required to serve (1) a new user or (2) a change in use, the facilities constructed, extended, or modified shall be designed to be capable of providing, for a sustained period of at least two hours, in addition to the requirements of the average daily demand within the area to be served, the minimum flow requirements set forth below opposite the classification of land use to be served:

Land Use Minimum Flow
1. Rural, residential with a lot density of two or
fewer units per acre primarily for
recreational and retirement use 250 gpm
2. Lot density of less than one single-family
residential unit per acre 500 gpm
3. Lot density of one or two single-family
residential units per acre 750 gpm
4. Lot density of three or more single-family
residential units per acre 1,000 gpm
5. Duplex residential units, neighborhood
business of one story 1,500 gpm
6. Multiple residential, one and two stories;
light commercial or light industrial 2,000 gpm
7. Multiple residential, three stories or higher;
heavy commercial or heavy industrial 2,500 gpm